It's a hook to hang pictures from. It was set on a piece of picture moulding which ran around the perimeter of the wall, up near the ceiling, and the picture wire was long and hooked onto it.
Hello, This is interesting because I have a room up north with picture molding around the room. I guess we should have a side view to see the configuration of hanging lip and the picture wire holding. Thank you both for posting another fascinating thing that we just overlook and stuff. RED Matthews
Hey , Red. If you look at the pic Pam posted of the hook, the lower tip is where the wire goes. If you turned it on it's side , it would have a larger semi circle shape that would hang nicely on your moulding. I've owned a number of them and I have also dug them. There are a lot of different designs for these old picture hangers.